Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
- 2 -
The present invention relates to a photosetting .
adhesive composition which is harde~able by irradiation under
u.y. light and which is particularly effective as an adhesive
for glass, and to its applicatlon for the bonding of glass
to glass or other substrates especially plastics, e.g. as in
the manu~acture of laminates such as safety-glass laminates for~;
the construction of houses and other buildings (window-panes,
glass-partitions, etc.) and armoured glass, and in the manufac~ure
of insulated glass (double glaæing).
,, " .
According to the common techniques presently in use,
laminated glass panels, e.g. the safety-glass laminates used
in the construction of buildings, are manufactured by inserting
a thin layer of clear thermoplastic materlal betwecn two glass
plates and, thereafter, heating the obtained assembly to
cause the individual elements of the lamlnate to strongly stick
together and to eliminate the air bubbles accidentally trapped
therein. This technique is time consuming and expensive because,
in addition to the time spent for heating, some more time must be
allowed for the slow cooling of the pieces to prevent possible
breakage due to thermal shock; further, this technique is not
''~
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~ 67~1~
- 3 -
adapted to continuous production. Moreover, thermoplastic materials
provided with a suitable refractive index which dlrectly adherç to
glass by melting or which can be glued thereto with known adheslves
are not common and are expensive ~e.g. polyvinylbutyral, polyurethanes,
`polycarbonates). ~lso, the use of classlcal adhesives is met wlth
the same difficultles as already mentioned before because heat must
ult;mately be used for the hardening step (thermosetting adhesives).
Further, at the time of use, the initial viscosity of such adhesives
is already reLatively high which makes them difficult to use as
very thin layers and to completely eliminate air-bubbles and other
internal defects trapped therein.
In order to correct the above deficien¢ies, novel
adhesive compositions with photo-hardening properties have
been developed recently. With such compositions, it is no
longer necessary to use heat since the adhesive properties are
deveioped by irradiation.
To be suitable for use in the production of glass
laminates, the adhesive must oE course be clear and colourless
and have a reEractive index like that of glass. For the production
of safety glass or armoured glass laminates, the adhesive must
also be capable of bonding not only to glass but also to plastics
materlals likely to be employed as interlayers ln the production
of the laminates, and it must be sufficiently strong and flexible
to absorb the stresses and strains set up in the laminate during
heating or cooling, due to the different coefficients of expansion
of the glass and plastics materlals employed in the laminate. It
must also not noticeably discolour or lose Its bonding strength
on ageing.
.. ~ '
~t - 4 -
Many photopolymerisable adheslve composltions have
- been proposed but none has been entirely satisfactory for the
production of laminates containing both glass and plastics layers
For example, French Patent 2001985 describes a
composition comprising an olefinically unsaturated ester
prepolymer, an olefinically unsaturated monomer copolymerisable
with the prepo]ymer and, of course, a photopolymerisation
initiator. This composition, a~ter introduction between two
glass plates, provides after u.v. irradiation a strong and
flexible bond. However, it employs as the prepolymer a
polyester which is expensive to manufacture and its adhesion
to some resins such as polyethylene and polypropylene is
inadequate, thus precluding the use of these common plastics
materials in the production of safety glasses.
French Patent Application 2347425 discloses a u.~.
polymerisable composition based on a polyalkeneoxy derivative,
polyglycol acrylates and optionally alkyl acrylates with long
chain alkyl gro~lps. These compositions after irradiation are
said to provide excellent adhesion to a variety of substrates
but they are not suggested to be suitable for the production
of laminated glass panels and their adhesive strength to those
plastics whlch are difficult to bond, e.g. polyethylene, is
not disclosed.
French Patent Application 2281968 discloses u.v.-
polymerisable adhesive compositions based on acrylic acid (II)
and an N,N-dialkylaminoalkyl acrylate or methacrylate (I) and
US Patent 3671502 discloses that the zwitter ion compounds (III)
,
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- 5 ^
known as betaines a~ll obtainable by the inter-reaction of these two
ompounds as lndicated below (where the use of N,N-dimethylaminoethyl
methacrylate as the ester is shown) may be copolymerised with
hydroxyalkyl acrylates to give copolymers useful as adhesives
for, e.g. glass, leather, plastics, steel, e~
O COOH O COO
CO N ~ ~ CO N
(I) (II) (III) -~
However, the adhesives dsscrbed in both these publications are
hydrophilic and, under moist conditlons~ their bond strength
deteriorates with time, a condition which may lead to eventual
separation of the elements bonded together. Moreover, the
adhesives described in this French patent application tend to be
.
rigid and to discolour on ageing,
Polymerisable compositions based on olefinically
unsaturated oligomeric compounds which also contain urethane
groups have been known for many years. In general, these arc
prepared by reacting a compound containing free isocyanate
groups with an olefinically unsaturated compound containing
a free hydroxyl group.
For example US Patent 3425988, published in 1969,
describes a sealant composition comprising (a) a monomer obtained
by reacting a hydroxyalkyl ester of acrylic or methacrylic acid
wlth a polyisocyanate (which monomer ls hereinafter referred to
for convenience as a "urethane acrylate") and (b) a free radical
~ ~.
1;7~'7
polymerisatlon initiator of the peroxy type; US Patent
3509234 (1970~ describes paint compositions that are curable
by electromagnetic radlation and comprising a film-forming
solution of a vinyl monomer and a "urethane acrylate"; and
German Offenlegungsschrift (OLS~ 2115373 (1971) describes
a photopolymerisable composition suitable for use in the
production of flexographic printing plates and comprising
a photosensitiser, an ethylenically unsaturated monomer and
a "urethane acrylate" obta~ned by reacting 2-hydroxyethyl
methacrylate with the polyisocyanate obtainèd by reacting :
2 moles of a diisocyanate with 1 mole of a polyethylene
glycol.
German OLS 2324822 (1973) to Loctite (Ireland) Limitecl,
and equivalent ~o BP 1430422, describes the use of a photo-
polymerisable composition based on the reaction product of a
polyisocyanate with a polymerisable acrylate ester having a
hydroxyl group or a primary or secondary ~mino group in the
alcoholic moiety thereof, as an adhesive for laminating glass
to glass. However, the polymeric products obtained by exposing
these compositions to u.v. irradiation are descrlbed as hard
and there is no indication that they boncl adequately or at
all to plastics substrates of the kind that would be of interest
in the production of safety glass laminates or armoured glass. Moreover,
BP Specification 1448257 (1976), also in the name of Loctite
(Ireland) Limited, describes how after a flexlble thermoplastics
tape coated on one side with such a composition has been applied
. .
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11~6~37
to a substrate and the composition polymerised in contact
with the substrate by u.v. irradiation, the tape may be peeled
away from the curecl adhesive composition without difficulty,
even in the absence of a release eoating between the tape and
the adhesive composltion, to leave the cured composition as a
coating on the substrate It is apparent ~rom this publieation,
therefore, that the polymerised composition c~nnot be expected to
bond strongly to thermoplastie materials.
Sinee the publieation of German ~LS 2324822, there
have been many publications, e.g. USP's 3862021 and ~018851
and French Patent Publication 2303835, proposing modificatlons
of these compositions, primarily by seleetion of the eomponents
forming the polyisoeyanate and/or polymerisable acrylate ester.
~ .
The present invention provides an adheslve eomposition
which reduces or overcomes most of the above-mentioned drawbacks.
In particular, by means of the invention compositions may be
obtained which on curing are glass clear and eolourless andwhich
bond strongly both to glass and to plastics materials9 even
those plasties materials which are diffieult to bond such as
polyethylene and polypropylene, and are suffieiently strong
and flexible to withstand the strains and stresses that occur
on heating or cooling glass/plastics laminates due to the different
eoefficients of expansion of glass and plastics.
~ ccorcling to the present invention, there is provided
a photohardenable eomposition polymerisable by irradiation under
.
.
.~
. .
.
~L76t7~'7
- 8 -
u.v. light to provide an adhesive, and including:
A~ at least one photopolymerisable prepolymerhaving an olefinic double bond activated by an electrophilic
substituent,
B. a polymerisation photoinitiator,
C. a substituted or unsubstituted aliphatic or
cycloaliphatic N~N-dialkylamino alcohol ester of an alpha,
beta-ethylenically unsaturated carboxylic acid, said alcohol
having an alkylene moiety of up to six carbon atoms between ~`
the hydroxy and the amino functions, and .
D. an alpha,beta-ethylenically unsaturated carboxylic
acid in an amount of one mole per mole of C, and
~w .
wherein ~C) and (D) are capable of reacting together to form a
betaine and said oligomer or prepol~mer (A) is an ester of an
alpha,beta-ethylenlcally unsaturated acid and a hydroxylated product
containing one or more urethane and/or urea links in the molecule
thereof and having a molecular weight from about 500 to 10000.
As betaines are ionic salts ln character, it would have
been expected that compositions containing both compounds capable of
reacting together to form a betaine and an organic prepolymer such
as (A) would form two phases and therefore the production of strong
clear colourless adhesives from the composltions of the invention
is most unexpected.
- In fact, by means of the lnvention, compositions can be
obtained having remar~able adhesive properties toward most usual
substrates, namely glass, minerals, metals, wood and plastic
materials and resins, and a surprising affinity for some substances
i7~
- 9 -
well known to be difficult to be glued or cemented together without
preliminary surface treatment, namely polypropylene ~PP~,
polyethylene (PE), polycarbonates (PC), polymethylmethacrylates (PM) ~;
(Plexiglass~ Lucite~ etc.) and polyvinylchloride ~PVC)
Thus, the invention also provides a method of bonding
a face of a material that is transparent to u.v. radiation to
another face of the same or different material by providing a
layer of the composition between the faces and then subjecting said
layer to u.v. irradiation to cure the composition and bond the
faces together.
- The invention is particularly applicable to the
bonding of glass to glass or to other materials, especially
plas~ics and more particularly the relatively cheap and readily
avallable plastics listed above. Thus one particularly preferred
aspect of the invention is the production of a clear laminate by
bonding a sheet of glass to a transparent plastics lamina which
may be, for example, a sheet of organic gLass or a thin flexible
transparent plastics film intended to be used as an interlayer between
two glass sheets or between a sheet of glass and a sheet of organic
glass. Thus, by means of the invention shock resistant glass
laminates, especially safety glass and armoured glass, can be
prepared from such plastlcs materials, which was impossible with
the known adhesives of the prior art.
Another important aspect of the invention is in the bonding
of glass to wood, wood products or metal~ especially aluminium,
e.g. the bonding of glass elements to frame members in the production
of double glazing units of the kind known for thermal and/or sound
insulation.
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1 0
Yet another important aspect of the invention is in the
bonding of one transparent plastic to another transparent plastic,
e.g. in the bonding together of two sheets oE organIc glass~ which
may be formed of the same or different polymeric materlals, e.g.
polymethylmethacrylate and polycarbonate optionally with the
lnterposition between the two sheets of a thln flexible transparent
plastics film as, for example, in the production of some forms of
armoured or bullet-proof glass.
Component A may be regarded as the product obtained by
esterifying the alpha,beta-ethylenically unsaturated carboxylic
acid with an oligomeric compound containing at least one free
hydroxyl group and also at least one urethane and/or urea group.
~~ It may be formed, for example, by reacting an ester of the acid
wherein the ester moiety contains at least one active hydrogen
atom, preferably a hydroxyester, with an isocyanate containing at
least one free isocyanate group. In the latter case, one or both
of the isocyanate and the alcoholic moiety of the ester will be
oligomeric.
Thus, in general terms, Component A may be regarded
as being made up of three components; namely the acid, an
hydroxy compound containing at least one other active hydrogen
atom which e.g. may be part of a hydroxyl or an amine group,
and an isocyanate compound containing one or more free isocyanate
groups. One orboth of the hydroxy compound and isocyanate
compound may also contain olefinic unsaturation.
As the hydroxy compound may be employed, for example,
diols, polyols, and compounds containing at least one hydroxy
group and one or more amino hydrogen atoms, e.g. glycols,
glycerols, polyalkyleneoxydiols, polyamine-glycols, diethanolamine,
v
aminoethanol, hydroxyethyl-ethylenediamine, hydroxyethylhexamethyl-
enediamine, etc. and mixtures thereof.
As the polylsocyanate may be employed, for example,
toluene diisocyanates, 4,~'-diphenyl dlisocyanate, 4,~'-diphenyl
alkane diisocyanates,dianisidine diisocyanates, 1,5-naphthalene
diisocyanate, 4,4'-diphenyl ether diisocyanate, p~phenylene
diisocyanate, trimethylene diisocyanate, tetramethylene diiso-
cyanate, hexamethylene diisocyanate, ethylene diisocyanate,
cyclohexylene diisocyanates, nonamethylene diisocyanate, octo-
decamethylene diisocyanate, 2-chloropropane diisocyanate,
2,2'-diethylether diisocyanate, 2-(dimethylamino) pentane
diisocyanate, tetrachlorophenylene-1,4-diisocyanate, 3-heptene
diisocyanate and transvinylene diisocyanate.
If the isocyanate compound contains three or more
isocyanate groups or the hydroxy compound contains three or
more active hydrogens, branched products may be obtained, e.g.
by reacting x molecules of an hydroxyester of the acid with
one molecule of an isocyanate having x isocyanate groups where
x is three or more. Such an isocyanate may be prepared for
example by reacting x molecules of a diisocyanate with one
molecule of a compound having x active hydrogen atoms, such
as trimcthylol propane, glycerol or pentaerythritol.
~ lowever, where a low viscosity adhesive composition is
required, it is generally preferred that component A is substantially
linear and derived from the acid, one or a mixture of hydroxy compounds
containing on average about two (e.g. 1.8-2.2) active ~l atoms, and
one or a mixture of isocyanates having on average about two (e.g
1 8-2.2) isocyanate groups.
~l~L76~
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- 12 -
In a preferred form, component A is substantially
linear and may be regarded as being made up of the acid, a
diol component and a dilsocyanate component.
For example, the acid may be reacted with the diol
component in about 1:1 molar ratio to form an hydroxy ester
of the acid which is then reacted in a 1-2:1 molar ratio with
the diisocyanate component, or a diol may be reacted in a
molar excess with a diisocyanate to give a dihydroxy-terminated
urethane ollgomer which is then reacted with up to two moles
of the acld. Thus component A can be a mixture of linear compounds
with an average level of olefinic unsaturation per molecule, due to the acid, !'
of between 1 and 2.
Mixtures of acids, diols and/or isocyanates may be
employed and one or both of the diol and isocyanate may
itself be oligomeric to provide the necessary molecular weight
in the product. '
For example, where the diol is oligomeric, it may be
a polyester-,polyethe~ or polyurethane -diol (e.g. obtained by
reacting a low molecular weight diol wlth a diisocyanate in a
molar ratio of in excess of 1 up to 2 moles of diol per mole
of diisocyanate). Where the isocyanate is ollgomeric, it
may be a polyurethane, polyurea or a polymer containing both
~ :'.
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- 13 -
urethane and urea groups, and may be obtained,for example,
by reacting a low molecular weight diisocyanate with a diol
(which may be a polyether or polyester, for example) in a molar
ratio of more than 1 mole up to 2 moles of diisocyanate per
mole of diol.
Examples of preferred low moLecular weight diols
are ethylene glycol, propylene glycol, diethylene glycol,
neopentyl glycol, bisphenol A, i,4-dimethylol-cyclohexane and
butane-1,4-diol and examples of oligomeric diols are the dihydroxy
terminated homopolymers and copolymers of ethylene oxide and
propylene-1,2-oxide and the dihydroxy terminated polyesters and
copolyesters of one or more of the above-mentioned low molecular
weight diols with one or more dicarboxylic acids such as s~cinic
acid, glutaric acid, adipic acid, pimelic acid, suberic acid,
... .
azelaic acid and sebacic acid.
Examples of preferred low molecular weight diisocyanates
are alkylene diisocyanates such as hexamethylene dlisocyanate and
aromatic diisocyanates such as toluene diisocyanates, xylylene
diisocyanates and bis(isocyanatophenyl)compounds such as bis(4-
isocyanatophenyl) methane and 2,2-bis~4-isocyanatophenyl)
propane.
The acid is suitably a monocarboxylic acid such as
acrylic acid or an alpha-substituted derivative thereof where
the substituent is e.g a lower alkyl group, halogen or cyano,
e g. as in methacrylic acid.
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- 14 -
Component A has a molecular welght of 500 to 10,000
and preferably about 1000 to 5000. Particularly good clarity
and the ability to adhere to a wide ~ariety of
plastics materials are obtained when component A is based on a
flexible oligomeric polyol and an isocyanate in which the free
isocyanate groups are not linked together by a long chain
alkylene group whereby the isocyanate may be regarded as a
substantially rigid molecule, e.g. as in cycloalipha~ic and
substantially aromatic isocyanates.
Preferably component A has one olefinically unsaturated
group for each ôOO-3000 of molecular weight, on average.
~...
The compounds A are therefore unsaturated esters of
macromolecular hydroxy compounds comprising in their back-bone
one or more urethane and/or urea bridges which result from the
`reaction of the -NCO groups of the isocyanates with the -OH or
-NH2 groups, respectively, of the e.g, polyols9 polyamines or amino-
alcohols.One is therefore dealing with polyurethane-poly~rea olef-
lnic monomer-oligomers many types of which are offered on the
market under various registered or fancy names.
Component A preferably forms from 10 to 95% of the
total welght of the composltlon.
Components C and D together preferably form 1 to 10%
by weight of the total of the composltion. Quantities hlgher
than 10% may impart to the adhesive after polymerization some
level of hydrophilicity which may be detrimental for certain
applications, namely when the laminate manufactured with the
present composition must ultimately be used under moist conditions.
~L~7~i71~1'7
t~
- 15 - -
On the other hand, if the combined welght of components
C and D is below 1%, the acti~ity of compounds (I) ~nd (II) is
less than within the above mentioned limits. However, in some
special cases, it may become desirable to use amounts above 10%
or below 1%, namely when it is desired to impart special
properties to the present adhesive.
Components C and D preferably have the followlng
formulae
; Rl R2 4 R3
Q ~ 5 R CH ~ - COOH
(IV) (V)
in which the Q-Q link represents a straight or cyclic hydrocarbon
connecting group of up to 6 carbcn atoms, R to R represent
H or lower alkyl groups, R and R are lower alkyls and R is H or
a -COOR group where R is H or a lower alkyl (i.e. Cl-C4 alkyl).
Component C may result from the esterification, by
usual means, of a tertiary-amino-alcohol H ~Q-QR -NR R with
an acrylic or substituted acrylic acld CH2=CR -COOH. Typical
examples of such amino-alcohols are, dimethylaminoethanol,
N,N-dimethyl-2-aminopropanol, N,N-diethyl-aminoethanol,
N,N-dimethyl-3-aminopropanol, N,N-diisopropyl-3-aminopropanol,
N,N-dimethyl-3-aminobutanol, N,N-dimethyl-2-amino-3-butanol,
N,N-dimethyl-4-aminobutanol, N,N-dimethyl-S-aminopentanol,
N,N-dimethyl-4-aminocyclohexanol and N,N-dimethyl-2-amino-
cyclohexanol. Examples of acids are acrylc and methacrylic
,
,:
- 16 -
acids and other derivatives of such compounds, not expressly
covered by the above formulae, e.g. ilalogenated and cyano-
substituted derivatives.
Component D is an alpha,beta-ethylenically
unsaturated carboxylic acid such as acrylic acid, methacrylic
acid, maleic acid, fumaric acid or the monoestcrs of these
dicarboxylic acids.
It is also possible to use in the present composition,
instead of the additives represented by formulae (C) and (D),
the 7witter ion or betaine compound obtained by mixing these
compounds together. There is evidence that these substances
react one with the other on simple admixture because, after
mixing stoichiometric quantities at room temperature, there
is an evolution of heat. Practically, ater leavlng (C) with
(D) to stand for a few hours, the desired quantity of the
mix~ure is added to components A and B. Where the betaine
is employed in place of the ~ixture of C and D, it may also
be derived by other means, e.g. by the reaction described -;
in US Patent 2548428. However, in general, because it is more
economical, it is preferred to directly mix together all ingredients
of the composition, that is components A, B, C and D optionally with
other additives if desired, e.g. stabili~ers, activators, etc. and
leave the mixture to stand at room temperature for allowing the
reaction between C and D to take place and, also, other possible
reactions between C, D and the other olefinic monomers. Of course,
f, ~L17~5~157
- 17 -
no confusion should be made between the above-mentioned reaction
and the subsequent photopolymerization reaction of~tl-e adhesive.
- The present composition may also contain in addition
to components A-D, at least one copoLymerisable olefinically
unsaturated compound, E, which may be monomeric or oligomeric
in nature.
The range of olefinic monomers and oligomers suitable
as component E in the present invention is wide. Indeed9 most
of the olefins which are in liquid form at room temperature and
at leas~ one of the double bonds of which is ac~ivated by a
suitable substituent are convenient, Typical activator sub-
stituents for this double bond are the groups halogeno, keto,
~``cyano, nitro, aryl, etc., when located in the ~ -position
relative to said double bond.
It is to be understood that in the composition of the
inven~ion, component E may be provided in whole or in part by an
excess of component C or, more preferably, component D over the
equimolar proportion specified for these materials. In fact, in
one preferred embodiment, compound E is satisfied at least in part
by having component D present in an amount in excess of equimolar
with component C, especially where D is acrylic acid.
Overall, where one or other of C or D is present in excess
it is preferred that components C and D are present in molar ratios
of from 2:1 to l:l00.
~ n exhaustive range of compounds which can be used as
or in component E can be found in the above quoted references and in the
~YU`i`~ r~
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i7~7
18 -
following ones:
USP 3,759,807; J. C. MILE0, "Analyse de la lltterature des
brevets sur la formulation des liants radio-d~1rcissables",
~evue de l'Institut francais du petrole 31, (5), 823 (1076).
As examples of preferred olefins, the following can be mentioned: r
acrylic, methacrylic, cyano-acrylic and chloroacrylic acids and
esters of lower alkyl groups, polyol acrylates, cyanoethyl
acrylate, trimethylol-propane triacrylate, acrylamides and
corresponding derivatives, arylolefins such as styrene, allylbenzene,
allyl phthalate, etc.
Oligomers and prepolymers of category E can be, for
instance, hemi~esters resulting from the reaction of a polyol
with about one equivalent of maleic anhydride per -0ll equivalent
of the polyol; oligo-amides and oligo-ester-amides of maleic
anhydride obtained by the reaction thereof with, for example,
di- or polyamines; lower molecular weight co-polymers of
alkenyl acrylates and methacrylates with hydroxy-alkenyl
compounds; esters of ~-unsaturated fatty acids, etc.
It should be stressed that one of the further advaneages
of the invention resides in the multiple possible variations of the
olefinic portion of the adhesive composition. Indeed, in contrast with
the other adhesive products of the prior art, it is possible to use
in the present composition, depending on the desired viscosity
before photopolymerization, very simply structured olefinic
monomers (such being therefore very free-flowing liquids) as
well as relatively high molecular weight oligomers or prepolymers.
Thus, it will be possible to control the formulation of the olefinic
',
'7
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- 19 -
portion of the compositivn according to the needs and as a function
of the starting viscosity desirable for any type of application.
Component E preferably forms from 0~001 to 60~/u of the
total weight of the composition.
It should be noted that, in the case of the invention,
the presence of the amino compound (C) or rather its reaction
product with (D), appears to hare an activating ef~ect on
the rate of the photopolymerization. This effect, which constitutes
one further advantage of the invention, is very surprising because,
although it is known that some amines can act, together with certain
photoinitiators, as photopolymerzatlon activators (see for instance
M.R. SANDNER, C,L. OSBORN and D.J. TRECICER, Benzophenonetriethylamine
Photoinitiated Polymerization of Methyl Acrylate, G. Pol. Sci. 10,
3174 (1972)), quaternary ammonium salts did not seem to ~ ve such
properties.
In the present composition, it is possible to use, as
photoinitiator ~, most classical photopolymerization initiators.
A useful list of such initiators can be found in US Patent No
3,759,807. In the present invention, some of the preferred initiators
are benzoin, acetophenone, anthraquinone, benzophenone and
naphthophenone because of availability and price considerations.
However this list is not exhaustive.
The quantity of such photoinitiator in the present
composition can preferably range from about 0.001 to 10% by
weight of the total composition. When the quantity of photo-
initiator is below 0.001% by weight, the photopolymerization is
P~ 7~
,~ :
generally too slow to be practical. Quantities above 10% are
generally not requirecl, are not advantageous economically and can
have a detrimental effect on some properties of the adhesive.
For fabricating laminates, the present cornposition may
be applied as follows: once the various ingredients have been mixed,
and after a period ~or allowing the various possible reactions between
the ingredients to come to equilibrlum, the adhesive composition
is applied to one or both facing sides of the substrates to be
assembled together, then such substrates are brought together by -~
superimposing one onto the other so as to eliminate, e.g. by application -~
of pressure, all air-bubbles and othar defects possibly present between
said substrates; then~ the assembly is irradiated by means of an
adequate actinic source according to usual practice. ~aturally,
at least one of the substrates must be transparent to the photo-
radiation used. For this, one works in the ultra-violet spectrum
at a wavelength appropriate for the photoinitiator employed and for
a time sufficient to produce the polymerization of said composition.
By means of the invention it is possible to achieve very
high values of adhesion of glass to a substrate such as plastic, wood
or metal within very short irradiation periods (for instance from
between 0,5 and 30 sec. to a few minutes, depending on the source power
and on the wavelength~. Adheslve values, measured according to the
Standard Test called "T peel test" and described ln ASTM D 1876-69
Standards, can attain 10-50 N/inch. These values are only temporarily
lowered when the laminate ls boiled with water or subjected to
treatment with superheated steam (e.g. at 117C).
: . . ,
,
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~ 6~7
;~ 21
The adhesive layer can be applied at w~ll on one or both
of the facing sides of the elements to be glued togetller. Thls
application can be carried out manually, for example by means
of a brush or a pad soaked in the photopolymerizable compositlon,
or by any suitable mechanical means.
The thickness of the adhesive layer, expressed in grams
per unit surface area, can be between 0.1 and 20 g/m2 or even exceed
such limit. Best adhesion results, especially when the laminate is
subjected to long exposures to moisture, are obtained when using about
5-10 glm2 of the adhesive.
The irradiation period required to achieve the polymer$zation
of the adhesive is directly related to the time after which the
minimum dose of radiation of proper wavelength has been absorbed by
the adhesive layer. It therefore essentially depends on the
spectral distribution of the source, on the power thereof, on the
distance thereof from the substrate to be irradiated and on the -~
optical transmission of that layer of the substrate which must be
penetrated by the light before reaching the adhesive itself. Thus,
glass and synthetic resins all have some sign$ficant extinction
coefficient in the UV range and, consequently, the irradiation
duration must be adapted to the optical propert$es of each material
used.
As irradiation sources, any havlng an emission spectrum largely
comprised ahove 0.3 r is convenient, e.g. mercury vapor lamps. ne
or more lamps of 20 W to about 10 KW can be used, e.g. a 2 kW lamp
of type IITQ7 made by P~IILIPS or a high-pressure mercury vapor lamp
s,~, .
`` ~17671~ ;
- 22 -
,~ ,.
giving 80 W/cm made by ~IANOVIA Argon or krypton lamps can
also be used.
Preferably, the polymerization is carried out only by
irradiation with no further heat than that resulting from the light
sources. In gener~l, it is not necessary that such heat be removed,
e.g. by cooling. The present adhesive can be applied to the continuous
or the discontinuous manufacture of laminates.
By means of the present invention, compositions may be
obtained which are suitable for cementing most of the usual solid
substrates: wood, metals, paper, glass, minerals, ceramics,
plastics, etc. ~lowever, an important aspect of`the invention is
in the provision of adhesive compositions useful for the manu~acture
of glass-to-glass and, especially, plastics-to-glass laminates.
In particular~ the invention enables a wide choice of
transparent plastics having satisfactory optical properties ~or
laminating wlth glass. Thus, by means of the invention inserts of
polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC),
polyurethane,polyester, polyamide, polycarbonate, polyacrylic
resins (which term includes methacrylate resins)~ polyvinylbutyral,
etc" may be employed using very economical operating conditions since the
compositions can be provided in a form which is easy-flowing before
polymerization and which can therefore be worked easily and the air
bubbles being possibly trapped between the layers of the laminate
cab be squeezed away by the application of only slight pressures.
Moreover, by means of the invention, compositions can be provided
which are particularly suited for semi-continuous working operations
~ ' '' `',
'7~
i~
- 23 -
since irradiation takes only a few seconds or minutes and no slow
heating or cooling of the glass is required.
It must be emphasised that the present adhesive is
particularly valuable for the production of laminates which comp~lse
organic glass elements instead of the usual corresponding mineral
glass plates. Using hard pieces of transparent synthetic resins in
place of glass for the manufacture of safety and shock-proof clear
laminates is a modern technique aiméd at producing lighter
although very resistant materiais which are more convenient to
handle and will save building labor costs. Such hard transparent
plates can be made available from resins such as polymethacrylates,
~: hard PVC, polycarbonates, polyurethane, etc., which cannot be assembled
by usual means or by using usual adhesives. Thus, for instance,
if composite glass laminates comprising such an organic glass plate,e.g.
a polycarbonate plate,sandwiched between two glass plates are assembled
together by inserting PYB intermediate sheets and heat treating,
the organic-glass element will be damaged by heat. On the other
hand, if assembly of the glass plates to the organic glass plate
is achieved by using conventional adhesives, the bonding strength
is inadequate or the relatively low flexibility of the adhesive will
not bc sufficient to accomodate the difference in thermal expansion
between the mineral and organic glasses and loss of bonding
and optical properties will result with time.
For the above reasons, another valuable use of the
invention is in the bonding of plastics to plastics, the plastics
being the same or different.
~g , .
;71~7
24 -
The reasons why the present adhesive adheres so wPll to
relatively inert polymers such as polyethylene are not known but it
is supposed that~ during lrradiation there may occur a certain
degree of grafting between the polymer chains of the substrate and
that of the adhesive. Whatever will happen exactly, it is not
rare to achieve with adhesives of the present invention bonding
strengths between the substrates in the order of lOQ0-2000 ~cm2
and peel strenghts of 10-50 N/inch.
It must be noted that the present adhesive composition
can also be used for the manufacture of glass laminates without
any plastic insert between the glass elements, e.g. by provlding
a suitable gap between the glass slabs by means of braces or
cross-bars, such gap being filled up with the adhesive composition.
After irradiation and hardening, the present adhesive thus replaces
the usual plastic inserts, which condition is quite possible
in view of the excellent flexibility and resistance to mechanical
and thermal shocks even at relatively high thicknesses of the
polymerized adhesive (e.g. film inserts are about 0.5-1 mm whereas
ordinary cementing layers of adhesive may be about 20-20 ~ thLck).
In summaryt adhesive compositio~s may be obtained
according to the invention having the following remar~able
properties:
1 A combination of a hydrophobicity sufficient for
~ ;tt\S~n~
articles fabricated using the adhesive to ~J}~ aR~ exposure to
humidity and rain for an extended period, with the ability to adhere
strongly to hydrophilic surfaces such as of glass and other
similar materials.
7~l7
,.~
- 25 -
2, I.xccllent adhesion towards such diversc plastics
materlals as PVC, PE, PP, PM (Plexiglass, Lucite), polycarbonates
(PC), polyurethanes (PU) and other synthetic resinsO
3. Excellent clarity and lack of colour and a
refractive index compatible with that of glass.
4. The ability when employed to produce laminates
between sheets, plates or foils having differcnt coefficients
of thermal expansion, e.g. glass and plastics, to withstand
consider~ble variations in temperature without rupture or
other damage caused by ~he stresses set up due to differing
expansion or contaction of the individual elements of the
laminate,
5. Good ageing characteristics.
6. The ability of safety and armoured glass laminates
.~
prepared using the adhesive to successfully withstand mechanical
and thermal shocks and extended vibration stresses. In this
connection, it should be noted that in the absence of compound
A in the composition, the adhesive can under the influence of
prolonged vibration undergo slow degradation and eventually
lose its transparency and bondlng properties.
7. The ability by suitable choice of the chemical
constitution, molecular weight and concentration of the compound
A, to minimise the volatility of the composition before
irradiation and thus toxicity hazards, ventiLation problems,
fire hazards, etc., and to adjust the viscosity of the
- 26 -
composition before irradiation within wide limits. This last
factor is important because, in the manufacture of laminates,
a device for assembling the flat elements thereof can include
small diameter pipes forflowlng the fluid aclheslve composition
to the substrates to be glued together and thin nose-tips for
distributing said liquid on the surfaces thereof. Thus, the
flow resistance of the fluid in such parts and therefore the -
pressures must be kept within acceptable limits compatible
with sufficient flow-`rates, low energy take-up and mechanical
strength of said device.
Advantages procured by the present invention over the
.-~ ` state of the prior art in the field of laminated glass are the
following:
The possibility of carrying out quick and semi-continuous
work, e.g. with bands of glass resulting from continuous
production ~float-glass) and with inserts provided from plastic
sheet rolls.
The elimination of problems inherent to the drying of
old adhesives by evaporation of the mixing solvents and of the
optical faults related to the bubbles caused by such evaporation.
The cancelling of the steps consisting in heating the
laminates to effect adhesion in special ovens working discon-
tinuously and in cooling the glass very slowly to avoid thermal
shock.
The use of an adhesive of low initial viscosity and
flowing more freely because it is in the unpolymerized state;
"~z .
d~ therefore, the possibility of using only a very small amount
;
'~
P~7~7~
- 27 -
thereof with equal or better cementing strength, wherefrom
great economy of material and strong reduction of the hazards
connected with the manipulatlon of acrylic monomers will be
achieved.
~~ A saving of energy since no heat is required and the
irradiation time is short.
The safety glass laminates obtained by applying the
composition of the invention are also part of the present invention,
namely the high mechanical strength glass la~inates comprising
in addition to the glass elements, elements made of "organic
glass" that is, for instance, polyurethane and polycarbonate plates,
with intermediate flexible transparent plastics films such as
of PVB9 PVC or soft polyurethane.
The following Examples illustrate the invention in more
detail.
Example 1
In a laboratory polymerization flask~ there were ~ixed
mechanically 930g of EBECRYL 220 (a prepolymer based on acrylic acid,
an aliphatic unsaturated polyester and an aromatic isocyanate and
having a molecular weight Mn of about 1000, containing about 11 meq/g
of oleflnic unsaturation and marketed by UCB7 Belgium) as component A,
40g of benzophenone, 7.3g (0.1 mole) of acrylic acid (D) and 15.7g
(0.1 mole) of dimethylaminoethyl methacrylate (C) (DMAEMA). There
was thus obtained a photopolymerizable composition.
This composition was evenly deposited on one side of each
of two glass plates (50 x 50 cm; "float-glassl' type) 4mm thick,
~rrade ~
76t7~3~
- 28
then the two plates were joined and pressed together (pressure
0.4 N/cm2) so as to obtain, between them, a liquid adhesive
phase of 0.1-0.2 r~. The assemhly was irradiated 5 min by
means of a mercury--vapor lamp, Type ~Q7, 2kW, 28 W/cm (obtained
from the Deutsche Philips GMBH) placed at 15 cm distance.
After irradiation a sample was cut irom the laminate (2.5 x
2 5 cm square) and subjected ~o a pulling resistance test according
to the American Standard Test ASTM D-1344-57 (1965). For this,
~here was attached on each side of the square a device for applying a force
tending to pull apart the two bonded elements thereof, thls force
being directed normally to the square surfaces of the sample. Then
the sample ~as sub~ected to~such forces by means of an INSTRO~testing
., .
apparatus and it was recorded ~hat the resistance to separation
was 1500 N/cm .
Example 2
Adhesive compositions labelled (C), (D) and (E) were
prepared as described in Example 1 with the following ingredients:
(C) UVITI-~NE 782 (a prepolymer based on acrylic acic~ a saturated
aliphatic polyester and an aromatic isocyanate and having a
molecular weight Mn of about 5300 and about 0.4 me~/g of olefinic
unsaturation and marlcctcd by Thiokol Corpn), 920g , benzophcnonc
40g,DMAEMA 27.4g (0.175 mole),acryllc acid 12.6g (0.175 mole).
(D) UVITIIANE 782 lOOg,trimethylpropane triacrylate
820 g~benzophenone 40g,0MAEMA 27~4g acrylic acid 12.6g .
~ T~O~Q ~
,~ . I'
: ~ '
,. ..
~' ^t'
2~
(E) UVIT~IANE 782 150g,cyanoethyl acrylate 770g,benzophenone
40g,DMAEMA 27.4g,acrylic acid 12.6g.
Besides, ~here were prepared control samples, respectively
(F), (G) and (H~, with the same ingredlents and the same quantities,
except the DMAEMA and the acrylic acid that were omitted.
Laminate samples were prepared as described in Example 1
with each of the six above adhesive compositions andJ after
polymerization under identical conditions, samples were taken
and subjected to the same separation resistance tests. The
results are recorded in Table I below.
TABLE I
Resistance to separation (N/cm ?
C 1700
F (Comparative) 500
D 770
G (Comparative) 540
E 1160
H (Comparative) 670
`:
This Example shows the considerable importance on the
adhesive propertles of the present compositions after irradiation
of the presence of the DMAEMA and acrylic acid.
The Example also shows that using a large proportion of
a lower molecular weight olefinic monomer (to beneficiate from a
low initial viscosity) causes no inconvenience.
.~ ,
7~
~7 _ 30 -
The followlng adhesive mixture (% by weight) was
prepared:
EBECRYL 230 (a prepolymer based on an aliphatic
polyether, an aliphatic isocyanate and acrylic acid and
having a molecular weight Mn of about 5000 and about 0.2
- meq/g of olefinic unsaturation and marketed by UCB, Belgium) 31%
Acrylic acid 62%
D~AEMA 2.5%
Benzophenone 2.5%
Lauroylperoxide 2%
(about 1.1% of the acrylic acid provides component C and the balance
i6 component E)
This mixture was used to attach together two glass plates
as described in Examp~ 1 and two samples (I~ and (J) of such
laminate before irradistion were prepared. The first sample (I)
was irradiated for 5 min 9S described in Example 1, whereas sample
(J) was heated lhr at 110C after which it was allowed to slowly
cool down (3 hrs).
The separation resistance of the two laminates was
measured as described in Example 1 and ga~e the following results: `
(I) 1650 N/cm ; (J) 1750 N/cm . It can be seen from this
experiment how much operational time can be saved by using light
instead of heat for effecting the polymerization, the properties
of the hardened composltions being about equal in both cases.
.,
,
''' ~ '
~ .
;7~
~_.
;~ - 31 -
.
Examp l e 4
A composition (K) was made by mixing the following
ingredients (% by weight):
UVITHANE 782 45.5% r
Acrylic acid 45~5~/O
DMAEMA 4%
Benzophenone 5/O
(about 1~8~/o of the acrylic acid provides component C and the
balance is componeTlt E)
A controL composition (L) was prepared with the same
proportion of the same lngredients but replacing the UVIT~NE
by ac~llc acid; i.e. bringing the acrylic acid level to 91-/o
by weight.
; A glass plate (50 x 50 cm) 4 mm thick (float-glass) was
carefully degrease(l with a commercial detergent solution then
it was rinsed with water and methanol and dried. A layer of
composition (K) (30 g/m ) was applied to the plate after which
there was deposited on the adhesive layer a polyvinylbutyral
sheet (PVB) and air bubbles were pushed away by pressing slightly
which was very easy because the solution was so free-Elowing.
The PVB sheet, Type TROSIFO ~30, was 0.76mm thick and was provided
by DYNAMIT NOBEL, Germany.
A similar laminate was prepared with control composition
(L) and both laminates were irradiated as described in Example 1.
The laminates were thereafter subjected to the peel test
~ e ~a~k
'7~i7~7
;7
- 32 -
'
according to ASTM standards. For this samples 1 inch wide were
cut from the laminates and the force applled in parallel to
the plate which was just necessary to peeL off the bonded film
was measured. The results were as follows: Sample Kl (from the
laminate prepared with composition (K) 30-35 N/lnch; Sample Ll
tfrom the laminate prepared with (L) 35-40 N/inch.
Thereafter, the main laminates were completed as follows:
a new layer of adhesive was applied to the PVP side thereof
and a second glass plate was adhered to said coated side thus
producing, after irradiation, two new laminates? respectively
K2 and L2 prepared, respectively, with compositions tK) and (L)
above
The resistancesto separation by tractionwere then measured
on cuttings from laminates K2 and L2 and were found to be 1350
Njcm and 1530 N/cm2, respectively. Then, the laminates were immersed
in boiling water and subjected for 6 hrs to vibrations (3000 H~)
from a vibration generator. After that period, the tests were
repeated and it was noted that K2 had remained unchanged while L2
had lost its transparency and its mechanical strength was strongly
decreased. This test thus evidences the utility of the olefin
prepolymer with urethane functions as a component of the present
adhesive composition.
Example 5
The followLng adheslve compositions were prepared as
follows (% by weight):
'',
- 33 -
M UVITHANE 782 31.5%
Acrylic acid 63 5%
DMAEMA 2~5%
Ben~ophenone 20 5%
tabout 1.1% of the acrylic acid provides component C and the balance
is component E)
,~
O. UVITHANE 48%
Acrylic acid 48%
DMA~MA 2%
Ben~ophenone 2%
(about 0~9% of the acrylic acid provides component C and the balance
is component E)
By using the adhesive compositions tK from the previous
Example, (M) and (O) above, there were prepared, according to
the technique illustrated at Example 4, a series of laminates
of the glass-plastic-glass type. The nature of the insert
plastic sheets is specified in Table II below Vuring this
preparation, the peel resistance (ASTM) and the separation
resistance were successively measured as described in the
previous Examples. The samples studied and the test results
are recorded in Table II.
~ 34 _
TABLE II
Adhesive Insert sheet, Kind of glass Peel test Separation test
. composition of kind of plastic (N/lnch)traction force
the laminate (N/cm2)
K PVC soft, lmm Float, 4mm 75-80
K Polyurethane,
(PLATILON~401) " 67-70
M " " 45-601,100
K PVB Polycarbonate 75-80 940
(TROSIFOL 30mil) (MAKROLON~
: standard)
M " " 50-55 ~
~. o " " 55-60 740
_, .
K PVC soft tmm "70-75
M " " 60-65
O ~:
O Polycarbonate Float~ 4mm 70-75 810
(MAKROLON
standard)
K PVC soft lmm PVC hard70-75
(TAKIRON ~
M " " 60-65
70-75
K " PMM 27-30
. (PERSPEX
K " PMM . 55-60
(CELLIDOR ~
.~
7~7~7
35 -
This Example shows that glass laminates wlth Q wide
variety of plastic inserts can be prepared by means oE the present
adhesive all having acceptable to good physical properties.
Example 6
An aluminium sheet 40~u thick was heated 12hrs at 145 C,
then after cooling it was coated at the rate of 6 g/m with
composition M oE the previous Example. Then a 50~ thick poly-
ethylene HP sheet was applied to the coated side of the aluminium
sheet and the composite was photopolymerized 10-15 sec by the
means described in Example 1. The peeling strength of the obtained
composite was measured according to the description of Example L
and found to be 30 Ntinch In Pact, the adhesion was so strong
that the sheets tended to give up before they got separated. This
Example evidenced the surprising adhesion developed, after
polymerization, by the present adhesive toward very inert polymers
such as PE. In a similar manner aluminium can be bonded to a glass
sheet.
Example 7
A test similar to that of the previous Example was performed
using a 40~u polyamide sheet, a 50~ PE sheet and, as the adhesive, a
composition containing (by weight) UVIT~lANE 782 44%, acrylic acid 44%,
.5% as component C and the balance as component E~, DMAE~A 10% and
benzophenone 2%. After irradiation, the peel resistance was 30 Nlinch
.~J - 36 ~
which showed that using an excess of DMAEMA (above about 5%) did not
bring any particular improvement in the adhesion
,
- Example 8
Three adhesive compositions, respectively (P), (Q) and
(R) were prepared by means of the following ingredients (parts by
weight)
~.'
Acrylic Benzo-Viscosity
Composition UVITHANE 782 Acid DMAEMA phenone(cps at 22 C) .
P 25 50 2 2 1~0 s
,~
Q SO 50 2 2 750
R 75 SO 2 2 4350
(About 0.9 parts of the acrylic acid were provided as component C
and the balance of 49.1 parts is present as component E)
!~ The above compositions were used to prepare a series
of laminates a) to g)l with mineral and organic glass, the structure
of which is given in the scheme below, by stacking and
gluing together glass and plastic plates separated by film
inserts. The intermediate films were usually 0.76mm thick whereas
the plates themselves (glass or organic glass)were usually 4mm
thick) In the following Table thickness of the elements is
given in mm; further PC = polycarbonate; PVP = polyvinylbutyral;
PVC = polyvinyl chloride.
a) glass (4)-PVB(0.76)-glass (4)
b) glass (4)-PVC(0.76)-glass (4)
c) glass (4)-PVB(0.76)-PC(MAKROLON,4)
"
. .
o ~ ~ ;
~7~;7~1'7
;~ - 37 -
d) gLass (4~-PVB(0.76)-glass(4)-PVB(0.76)-glass~4)
e) glass (4)-PVB(0.76)-PC(MAKR~LON,4)-PVB(0.76)-glass(4)
f) glass (4)-PVC(0.76)-glass(4)-PVC(0.76)-glass(4)
g) glass (4)-PVC(0.76)-PC(MAKROLON14)-PVC(0.76)-glass(~)
r
After hardening by irradiation as described in the previous
Examples, the laminates were allowed to age for a few days after
which they were sub~ected to shock resistance tests as follows:
I. Dynastat Test (impact resistance I.R): In this test
a strip sample of the laminate (about 30 x 50 mm) is gripped
.
ln a vice, with part (about 25mm) sticklng out vertically
therefrom. This protruding part is subjected to a blow from
a hammering pendulum having a given amplitude and being placed
so as to hit the sample transversally at the lower dead point
o its swinging course, i.e. at the maximum kinetic energy.
The energy absorbed by the rupture of the sample slows down the
pendulum, the displacement of which on the other side of the break
point will be shortened accordingly. The exact point reached
by the pendulum is recorded by a check-pointer driven by the
pendulum in relationship to a scale directly calibrated in work
units (N cm) whereby the magnitude of the resistance of the sample can
be read directly.
II. Resistance to the impact from a steel ball (C.R.)
In this test a steel ball (2~08 kg) is dropped ~height 3 m) in
the centre of a laminate (60 x 60 cm) placed hori~ontally on a
square frame. The operation is repeated until the ball digs a hole
in the laminate and passes therethrough. The number of blows required
is then recorded as a measure of resistance to shock.
~ ;7~7
- 38 -i
The results recorded on the different laminates a) to g)
above and labelled, depending on the adhesive (P), ~Q) or (R)
used, ~s a)P, a)Q, a)R, etc. are given in Table III below. The
same measurements carried out on the two following commercial laminates
(prepared by conventional technlques, that is by fusion of the r
inserts) are also given in Table III.
Laminate 1) glass(4)-PVB(0.76)-glass (4)
Laminate 2) glass(2.4)-PVB(0.76)-glass(2.4)
TABLE III
Impact reslstance of a series of laminates
Example Resistance to separation I.R.(N cm) C.R. (number of blows~
N/cm2 ~ ~
a)P 1200 50
a)Q 1280 74 5
a?R 900 93 - `
b)P - 100
b)Q - 110 10 `
b/R - 62
c)P 860 920
c)R - 1030
c)Q _ 1010
d)P - 183
d)Q 249 -
d)R - 334 ~
e)P - 1170 -
e)Q _ 1220
e)R - 1110
.,
` ,
,
` .
,
,
_
Example Resistance to separation I.R.(n cm) C.R. (number of blows)
Nlcm2
__ ~ __ ___
f)R - 340
g)P - 854
g)~ - 1200
g~R ~ 980
Laminate 1 - - 5
Laminate 2 - - 4
The I.R. Values above show that a marked increase in
impact resistance is obtained when replacing one of the glass
layers by a polycarbonate plate. They also show the advantages
of the PVC over the PVB as insert sheets, which advantage
could not be implemented before the present inventlon for lack
of a suitable adhesive.
~ "
Glass lamlnates were prepared using two 4mm thick glass
plates separated by PVB sheets (0.76 mm) and bonded by adhesive
compositions (20~). The first laminate used the adhesive
described in Example 1 whereas laminate (2) was made with a
control adhesive of the following cOmpQsition (parts by weight).
Acrylic acid 44%
Acryl~mide 29%
DMAI'MA 14%
Benzophenone 3%
~ P~'~&;~7
- 40 -
After 2 min irradiation as described in Example 1, both
laminates were placed outdoors under full sunlight exposure.
After a month standing, sample (1) showed no sign o change
whereas sample (2~ had discolored badly (yellowlng).
Example 10
Glass laminates were prepared using two 2mm glass plates
bonded on each side of a 4mm polycarbonate plate with a-100
layer of adhesive and without using any intermediate film
sheet. The adhesives used were (1) the adhesive (IC) of Example
4 and (2) the control adhesive of Example 9, respectlvely. After
irradiation as a result of which the laminates were heated to
about 70C, there was obtained a perfectly clear laminate from
adhesive ~1) whereas the laminate made with control adhesive ~2)
cracked on cooling due to the inability of the cured adhesive
to sustain the forces resulting from the differences in contraction
between glass and polycarbonate.
Example 11
Three groups, respectively S, T and U,each of three adhesive
compositions were prepared using in each 50 parts by weight oE acrylic
acid (0.9 parts as component C and the balance as componcnt E),
2 parts DMAE~A, 2 parts benzophenone and variable quantities
(according to Table IV below) of UVITHANE 783, UVITHANE 788 and
EBECRYL 210 respectively. The Uvithanes are marke~ed by Thiokol
,
~ 7
4 1 -
Corporation and Ebecryl 210 is marketed by UCB, Belgium.
Uvithane 783 is based on acrylic acid, aliphatic
polyester and aromatic isocyanate, has a molecular weight Mn
of about 1~00 and about 2 meq/g of olefinic unsaturation.
Uvithane 788 is based on acrylic acid, aliphatic
polyester and aliphatic isocyanate, has a molecular weight Mn
of about 1350 and about 1.4 meq/g of olefinic unsaturation.
Ebecryl 210 is based on acrylic acid, aliphatic
polyester and aromatic isocyanate and has a molecular weight
Mn of about 1500 and about 1,0 meq/g of olefinic unsaturation.
Samples of laminates comprising either a 0.76mm
polyurethane film (PLASTILON) or a lmm flexible PVC film bonded
to glass were prepared according to the techniques described
in the previous Examples~ On each sample, a~ter 1 ~onth ageing,
the peeling strengths were measured as described in Example 4.
The results are shown in Table IV.
TABLE IV
Sample Polyurethane Peeling strength Film
prepolymer (N/inch)
(parts by weight)
Sl UVITHANE 783 (25) 75-80
S2 UVITHANE 783 (50) 30-40 ) PLASTILON
S3 UVITI~NE 783 (75) 60-65
T1 UVITHANE 788 (25) 20-25 ) PVC
T2 UVIT~NE 788 (50) 28-33
T3 UVITHANE 788 (75) 50
- , .
~7t~ 7
;~ .
2 -
Sample Poly~lrethane Peeling strength Film
prepolymer (N/inch)
_ _(parts by wei~ht)
Ul EBECRYL 210 ~25) 60-65
U2 EBECRYL 210 (50) 50-55 ) PLASTILON
U3 EBECRYL 210 (75) iO-35
Exam~e 12
Composition Q of Example & was used to bond a polypropylene
film (0.2mm) to plates of glass and of polycarbonate (MAKROLON). The
peeling strength after irradiation was 30 Nlinch in the case of glass
whereas in the case of polycarbonate it could not be measured since
~- the film broke before peeling off.
'^` .
'
.~ :
